This is the key point. Take me, for example - I learned to mask very early on, effectively taught by my mother, who's also autistic...as were her mother and her grandmother. The result of that family history is that it became a family "tradition" to teach the next generation how to hide themselves in plain sight. Yes, there's a lot of wilful denial that goes with that...especially since I was born in the late 70s, so for all of my childhood a diagnosis of autism went hand-in-hand with "go directly to the dreaded Special School and never have a normal life".
Anyway, I've been diagnosed at the age of 45, although I was strongly aware that I'm autistic for three years before that. I'm basically almost the stereotype - incredibly good at STEM subjects, an instinctive affinity with systems of any kind, and...I turned one of my special interests (computers) into a career that, while it hasn't always been incredibly lucrative for me, it very much is now. I have a wife, a daughter who's 28 (not biologically mine, but I don't really see a functional difference and neither does she), and a very happy life.
It can be done, depending on the exact presentation of course. I got here by carefully and painstakingly working with my difficulties, and constructing an environment around myself which minimised my apparent alien-ness and allowed me to play to my strengths.
It hasn't always gone well, of course. My wife and I had at least a decade of finding life together very difficult (not helped by external circumstances), and a diagnosis earlier (not to mention being part of a very helpful autistic community) would definitely have accelerated our progress towards the relatively stress-free life we enjoy now.
When it comes to interviews...for the last few years (since I began to identify as autistic) I've always told them up-front that I'm autistic. I explain what I may have difficulty with (eg I may take a few moments to formulate an answer to a question, but that's usually because I've already jumped to the answer and I'm just figuring out the best way to phrase it for my audience), and I'll always ask them not to take it personally if I avoid eye contact for more than a couple of seconds. I'll usually make a bit of a joke about it if I can, to relieve the tension; I've found that NTs tend to be taken aback when somebody's quite that open about something that's often been a taboo subject. I also encourage them to ask any questions they want about my autistic tendencies, even if they're not considering giving me the job.
Before that, I had all sorts of tricks I'd pull to hide it. For example, eye contact - I'd surreptitiously nudge my chair further away while taking my coat off to hang it on the back, hiding the deliberate action behind apparent clumsiness. That allowed me to fake eye contact by staring at the interviewer's nose instead, and being far enough away that they wouldn't notice.
I suppose the point of this semi-brain-dump (sorry) is...don't worry too much about the future. It's not a fait accompli that she's going to fail to integrate with the world, and every new special interest is another potential opportunity to find a career that she'll be able to embrace. The most important thing to my mind is giving her the tools that she needs to build a safe, comfortable and above all not-limiting environment around herself as she enters adulthood, and helping her be aware of her limitations without letting them be her focus.